Machine tool systems generally include a controller that executes instructions interpreted by the machine tool control software to generate commands for controlling the operation of the machine tool system, including the position of a tool that shapes or cuts a part. Many such machine tool systems include components that move along three linear axes, as well as components that move about one or more rotary axes. To accurately form parts using such a machine tool system, it is necessary for the controller to know the precise orientation of the rotary axes relative to the machine coordinate system.
In one exemplary embodiment of the present disclosure, a method is provided for use with a machine tool system having a controller, three linear axes of motion establishing the machine coordinate system and at least one rotary axis, for determining the orientation of the rotary axis relative to the linear axes. The method includes the steps of mounting a sphere to a component of the system, mounting a probe to a spindle of the system, rotating one of the sphere and the probe to at least three positions about the rotary axis, measuring a center of the sphere at each of the positions by using the controller to move the probe into contact with the sphere, computing, using the controller, a plane that fits the center measurements, and computing, using the controller, a vector normal to the plane that passes through a center of rotation of an arc that lies in the plane and fits the center measurements, the vector corresponding to the orientation of the rotary axis.
In a variant of the exemplary embodiment, the method further includes the step of calibrating the probe to the sphere by manually locating the center of the sphere using a test indicator, and using the controller to move the probe toward the center of the sphere from a plurality of directions to determine deflection offsets of the probe resulting from contact with the sphere in each of the plurality of directions.
In another variant of the exemplary embodiment, the measuring step includes contacting the sphere with the probe from various directions, using the controller to calculate a center point of the sphere from location data corresponding to points of contact between the probe and the sphere, repeating the contacting and calculating steps, comparing a difference between the calculated center points to a predefined tolerance threshold, and repeating the contacting, calculating and comparing steps until the difference is within the tolerance threshold.
The measuring steps of the exemplary embodiment include using the controller to direct the probe toward the sphere in a positive direction along an X-axis of a coordinate system of the probe until the probe contacts the sphere at a first contact point, direct the probe toward the sphere in a negative direction along the X-axis until the probe contacts the sphere at a second contact point, compute a first midpoint between the first and second contact points, direct the probe toward the sphere in a positive direction along a first path that is parallel to a Y-axis of the probe coordinate system and passes through the first midpoint until the probe contacts the sphere at a third contact point, direct the probe toward the sphere in a negative direction along the first path until the probe contacts the sphere at a fourth contact point, compute a second midpoint between the third and fourth contact points, direct the probe toward the sphere along a second path that is parallel to a Z-axis of the probe coordinate system and passes through the first and second midpoints until the probe contacts the sphere at a fifth contact point, and compute a first center point of the sphere relative to the machine coordinate system from location data corresponding to each of the contact points.
A variant of the measuring steps of the exemplary embodiments further includes using the controller to direct the probe toward the sphere in a positive direction along a third path that is parallel to the X-axis of the probe coordinate system and passes through the second midpoint until the probe contacts the sphere at a sixth contact point, direct the probe toward the sphere in a negative direction along the third path until the probe contacts the sphere at a seventh contact point, compute a third midpoint between the sixth and seventh contact points, direct the probe toward the sphere in a positive direction along a fourth path that is parallel to the Y-axis of the probe coordinate system and passes through the third midpoint until the probe contacts the sphere at an eighth contact point, direct the probe toward the sphere in a negative direction along the fourth path until the probe contacts the sphere at a ninth contact point, compute a fourth midpoint between the eighth and ninth contact points, direct the probe toward the sphere along a fifth path that is parallel to the Z-axis of the probe coordinate system and passes through the third and fourth midpoints until the probe contacts the sphere at a tenth contact point, compute a second center point of the sphere relative to the machine coordinate system from location data corresponding to each of the fifth through tenth contact points, compute a difference between the first center point to the second center point, and compare the difference to a predefined tolerance.
Another variant of the measuring steps of the exemplary embodiments further includes using the controller to compute measured radii of the sphere using the location data corresponding to each of the contact points, compare the measured radii to a known radius of the sphere, and identify the first center point as the center of the sphere if the measured radii fall within a predetermined tolerance of the known radius.
In another variant of the exemplary embodiments, the rotating step includes automatically moving the probe along with the sphere as the sphere is moved to different positions about the rotary axis. This variant may further include maintaining the probe at a constant radius from the center of the sphere as the sphere or probe is moved to the different positions.
In a further exemplary embodiment of the present disclosure, a method is provided for use on a machine tool system having a controller, three linear axes of motion establishing a machine coordinate system and a rotary axis, for determining a shift of the rotary axis. The method includes the steps of mounting a sphere to a component of the system that is rotatable about the rotary axis at a first location at a first distance from the rotary axis, rotating the component to move the sphere in the first location to a first set of at least three positions about the rotary axis, measuring a first set of center points of the sphere, one center point for each of the first set of at least three positions, by using the controller to move a probe mounted to a spindle of the system into contact with the sphere, computing, using the controller, a first plane that fits the first set of center points, mounting the sphere to the component at a second location at a second distance from the rotary axis, the second distance being different from the first distance, rotating the component to move the sphere in the second location to a second set of at least three positions about the rotary axis, measuring a second set of center points of the sphere, one center point for each of the second set of at least three positions, by using the controller to move the probe into contact with the sphere, computing, using the controller, a second plane that fits the second set of center points, and comparing, using the controller, the first and second planes to determine a shift of the rotary axis.
In yet a further exemplary embodiment of the present disclosure, a method is provided for use on a machine tool system having a controller, three linear axes of motion establishing a machine coordinate system and a rotary axis, for determining a shift of the rotary axis. The method includes the steps of mounting a probe to a first component of the system that is rotatable about the rotary axis at a first location such that a tip of the probe is at a first distance from the rotary axis, mounting a sphere to a second component of the system, rotating the first component to move the probe in the first location to a first set of at least three positions about the rotary axis, measuring a first set of center points of the sphere, one center point for each of the first set of at least three positions, by using the controller to move the probe into contact with the sphere, computing, using the controller, a first plane that fits the first set of center points, mounting the probe to the first component at a second location such that the tip of the probe is at a second distance from the rotary axis, the second distance being different from the first distance, rotating the first component to move the probe in the second location to a second set of at least three positions about the rotary axis, measuring a second set of center points of the sphere, one center point for each of the second set of at least three positions, by using the controller to move the probe into contact with the sphere, computing, using the controller, a second plane that fits the second set of center points, and comparing, using the controller, the first and second planes to determine a shift of the rotary axis.
In yet a further exemplary embodiment of the present disclosure, a method is provided for measuring a rotary axis of a machine tool system relative to an X-axis, a Y-axis and a Z-axis of the system. The method includes the steps of mounting a sphere to a component of the system that is movable about the rotary axis, positioning the sphere in a first position at a first angle relative to the rotary axis, mounting a probe to a spindle of the system, determining a first center point of the sphere in the first position by using a controller of the system to perform a sphere center measurement operation, positioning the sphere in a second position at a second angle relative to the rotary axis, determining a second center point of the sphere in the second position by using the controller to perform the sphere center measurement operation, positioning the sphere in a third position at a third angle relative to the rotary axis, determining a third center point of the sphere in the third position by using the controller to perform the sphere center measurement operation, computing a plane that fits the first, second and third center points, computing an arc that lies in the plane and fits the X and Y coordinates of the first, second and third center points, computing a center of rotation of the arc, and identifying the orientation of the rotary axis as a vector normal to the plane that passes through the center of rotation.
In one exemplary embodiment, The sphere center measurement operation includes the steps of directing the probe toward the sphere in a positive direction along an X-axis of a coordinate system of the probe until the probe contacts the sphere at a first contact point, directing the probe toward the sphere in a negative direction along the X-axis until the probe contacts the sphere at a second contact point, computing a first midpoint between the first and second contact points, directing the probe toward the sphere in a positive direction along a path parallel to a Y-axis of a coordinate system of the probe that passes through the first midpoint until the probe contacts the sphere at a third contact point, directing the probe toward the sphere in a negative direction along the path parallel to the Y-axis until the probe contacts the sphere at a fourth contact point, computing a second midpoint between the third and fourth contact points, directing the probe toward the sphere along a path parallel to a Z-axis of a coordinate system of the probe that passes through the first and second midpoints until the probe contacts the sphere at a fifth contact point, and computing the first center point of the sphere within a three dimensional volume of the system using the first, second, third, fourth and fifth contact points, the center point having an X coordinate, a Y coordinate, and a Z coordinate.
A variant of the sphere center measurement operation of this exemplary embodiment further includes the steps of directing the probe toward the sphere in a positive direction along a third path that is parallel to the X-axis and passes through the second midpoint until the probe contacts the sphere at a sixth contact point, directing the probe toward the sphere in a negative direction along the third path until the probe contacts the sphere at a seventh contact point, computing a third midpoint between the sixth and seventh contact points, directing the probe toward the sphere in a positive direction along a fourth path that is parallel to the Y-axis of the probe coordinate system and passes through the third midpoint until the probe contacts the sphere at an eighth contact point, directing the probe toward the sphere in a negative direction along the fourth path until the probe contacts the sphere at a ninth contact point, computing a fourth midpoint between the eighth and ninth contact points, directing the probe toward the sphere along a fifth path that is parallel to the Z-axis of the probe coordinate system and passes through the third and fourth midpoints until the probe contacts the sphere at a tenth contact point, computing a second center point of the sphere relative to the linear axes from location data corresponding to each of the fifth through tenth contact points, computing a difference between the first center point to the second center point, and comparing the difference to a predefined tolerance.
In yet a further exemplary embodiment of the present disclosure, a method is provided for measuring a rotary axis of a machine tool system relative to X, Y and Z axes of the system using a probe mounted to a spindle of the system, including mounting a sphere to a component of the system, positioning the probe in a first position about the rotary axis, determining a first center point of the sphere by using a controller of the system to perform a sphere center measurement operation, positioning the probe in a second position about the rotary axis, determining a second center point of the sphere by using the controller to perform the sphere center measurement operation, positioning the probe in a third position about the rotary axis, determining a third center point of the sphere by using the controller to perform the sphere center measurement operation, computing a plane that fits the center points, computing an arc that lies in the plane and fits the X and Y coordinates of the center points, computing a center of rotation of the arc, and identifying the orientation of the rotary axis as a vector normal to the plane that passes through the center of rotation. The sphere center measurement operation includes the steps of moving the probe in a positive direction along an X-axis of a coordinate system of the probe into contact with the sphere at a first contact point, moving the probe in a negative direction along the X-axis of the probe coordinate system into contact with the sphere at a second contact point, moving the probe in a positive direction along a first path parallel to a Y-axis of a coordinate system of the probe into contact with the sphere at a third contact point, the first path passing through a first midpoint between the first and second contact points, moving the probe in a negative direction along the first path into contact with the sphere at a fourth contact point, moving the probe along a second path parallel to a Z-axis of a coordinate system of the probe into contact with the sphere at a fifth contact point, the second path passing through the first midpoint and a midpoint between the third and fourth contact points, and computing the first center point of the sphere using X, Y and Z coordinates corresponding to each of the contact points, the center point having X, Y and Z coordinates.
In still a further exemplary embodiment of the present disclosure, a method is provided for measuring a rotary axis of a machine tool system relative to X, Y and Z axes establishing a machine coordinate system using a probe mounted to a spindle of the system, including positioning a sphere in a first position about the rotary axis, determining a center point of the sphere in the first position by using a controller of the system to perform a sphere center measurement operation including moving the probe into contact with the sphere at five contact points corresponding to contact in a positive and a negative X direction, a positive and a negative Y direction, and a Z direction of a coordinate system of the probe, and computing a center of the sphere using coordinates of the contact points, rotating the sphere about the rotary axis into a second position, determining a center point of the sphere in the second position by using the controller to perform the sphere center measurement operation, rotating the sphere about the rotary axis into a third position, determining a center point of the sphere in the third position by using the controller to perform the sphere center measurement operation, calculating a centroid using the center points, transforming the center points such that the centroid is an origin of the center points, computing a plane that fits the transformed center points, projecting the transformed center points onto the plane, computing an arc that fits the projected center points, determining a center point of the arc, transforming coordinates of the arc center point into the machine coordinate system, and identifying the orientation of the rotary axis as a vector normal to a plane that passes through the transformed coordinates of the arc center point.
Corresponding reference characters indicate corresponding parts throughout the several views.